With a continuously growing population, it is becoming increasingly difficult to meet the world's energy needs as well as to control carbon emissions to kerb greenhouse gas emissions that are considered responsible for global warming phenomena. These concerns have triggered a drive towards more efficient energy consumption in an attempt to reduce energy consumption.
One such area of concern is lighting applications, either in domestic or commercial settings. There is a clear trend towards the replacement of energy inefficient incandescent light bulbs with more energy-efficient replacements. Indeed, in many jurisdictions the production and retailing of incandescent light bulbs has been outlawed, thus forcing consumers to buy energy-efficient alternatives, e.g. when replacing incandescent light bulbs. For example, the US government has initiated its Energy Star® programme, which includes a list of approved replacements of incandescent light bulbs such as compact fluorescent lamps and solid state lighting (SSL) devices, e.g. light emitting diode (LED)-based light bulbs.
It is generally recognized that SSL devices provide a particularly promising alternative due to their green credentials such as lifetime and energy consumption. SSL devices can produce a unit luminous output at a fraction of the energy cost of incandescent light bulbs. However, the commercial challenge with providing lighting devices based on SSL elements is to produce the lighting device at a cost point that makes the device accessible to large consumer volumes, as also recognized in the aforementioned Energy Star® programme. This is a far from trivial exercise. A typical SSL-based lighting device such as a light bulb contains several discrete components, such as a carrier for the one or more SSL elements, a carrier for the one or more SSL element driver circuits, a heat dissipating member to provide effective cooling to the electronic components on the various carriers, a reflector, beam shaping optics and so on, which makes the lighting device relatively complex and therefore costly.
Although it is technically straightforward to combine some of these components, e.g. a carrier such as a printed circuit board carrying both the SSL elements and the driver circuits, the impracticalities of such design choices cannot be easily overcome. For instance, the heat flux from a carrier on which both SSL elements and driver circuits are combined is such that this heat cannot be effectively dissipated by a heat dissipating member, e.g. a heat sink, thus causing overheating of the lighting device. For this reason, separate carriers are commonly used to delocalize the heat generation in the lighting device, despite the fact that this increases its manufacturing cost.
US 2012/0268936 A1 discloses a lighting element comprising plural heat sink regions on respective regions of a flexible circuit board, and plural light emitters on respective regions of the flexible circuit board. This however is a complex device that cannot be manufactured in a cost-effective manner.